Irritable bowel syndrome (IBS) is a functional digestive system disorder, meaning that no physical or structural cause can be found to explain the impaired digestive functions.
Nutrition can play a crucial role in the treatment of IBS. On a larger scale, the influence of diet on IBS has been examined in many clinical studies. While on an individual basis, many people affected have their own subjective theories about which foods they can tolerate and which one they can’t. This helps to explain why there are inconsistencies and incorrect information about the right diet for people with IBS.
Often, irritable bowel syndrome is mistaken for a food allergy or intolerance. Up to 50% of people with IBS report that their symptoms worsen after having eaten specific foods. Because of this, more than 60% of those affected restrict their diet based on their own suspicion of an allergy or intolerance. Sometimes people with IBS may also restrict certain foods to investigate for themselves how it may impact their IBS. These types of restriction, when extreme or prolonged, can result in** **malnutrition.
Finding a diet that works well for your IBS
With IBS, every case is different, so you may need to try a few things. Use a food and symptom diary or app to track the foods you eat and the symptoms that you experience can provide you with valuable insights.
People with IBS have sensitive digestive systems. It is not only relevant what you eat but also how, when, and where. The following general tips can help with your diet:
- Small meals: don’t eat large portions at once
- Mindful eating: eat slowly, chew consciously, and without distractions
- Hydration: drink enough water
- Reduction of alcohol, tea and coffee
- Mild food: avoid spicy, very salty, sweet or fatty foods
The low-FODMAP diet for IBS
FODMAPs are special carbohydrates found in certain foods. The acronym FODMAPs stands for fermentable oligo-, di- and monosaccharides and polyols. Some estimates report that about a third of patients with IBS are sensitive to FODMAPs. FODMAPs are not completely absorbed through the intestinal wall into the blood, leaving the surplus to be fermented by bacteria in the colon, causing gases to be produced.
In addition to the production of gas, which can irritate the intestine, FODMAPs also draw excess water into the intestine. The combination of these factors can lead to typical irritable bowel symptoms such as bloating, discomfort, and pain.
That’s why a low-FODMAP diet can help to alleviate symptoms. Since the low-FODMAP diet is mostly low in fiber, it is recommended to include non-fermentable fiber in the diet, such as psyllium. Taking probiotics can also make sense, since the low-FODMAP diet has an impact on the_ intestinal flora_ (or gut microbiome).
Food intolerances and specific carbohydrates (lactose, fructose or sorbitol) and IBS
Food intolerances are a major challenge with IBS. If you suspect that you are sensitive or intolerant to certain foods, these should be investigated by a qualified primary care provider or gastroenterologist. After the intolerance has been confirmed, you can form your individual IBS-friendly diet.
For some people, certain carbohydrates, like lactose, fructose, or sorbitol, are poorly absorbed through the intestinal wall. When these unabsorbed carbohydrates remain in the intestines, they are fermented by bacteria, and hydrogen gas is produced as a byproduct.
To diagnose a carbohydrate malabsorption (often referred to as an intolerance), a physician can perform a hydrogen breath test (H2 breath test). If a person tests positive, then that type of carbohydrate can specifically be omitted from the diet, which can help to alleviate IBS symptoms.
Celiac disease, wheat allergies, and IBS
People who have celiac disease (an autoimmune disease triggered by gluten proteins) are not able to eat products containing the wheat protein gluten. Gluten is a component of many common types of grains, including wheat, rye, barley, and spelt.
A wheat allergy can be caused by a reaction to various protein components found in wheat.
If a wheat allergy has been diagnosed by a physician (e.g. by a blood test [IgE], a skin prick test or by dietary methods), foods containing gluten and wheat should be eliminated.
Wheat and/or gluten sensitivity and IBS
If both wheat allergy and celiac disease may have been excluded, it’s still possible to have a negative reaction to wheat components. This is known as wheat sensitivity, and may be connected with IBS.
Some people, in rare cases, develop symptoms directly from wheat gluten components without having celiac disease. These people may report feeling better on a wheat- and gluten-free diet even without evidence of a wheat allergy, and presumably have non-celiac gluten sensitivity (NCGS). The extent to which wheat allergy or non-celiac gluten sensitivity (NCGS) plays a role in IBS has not yet been clearly clarified.
To date, there are no diagnostic tests for wheat sensitivity, so the diagnosis, like IBS, is a diagnosis of exclusion.
Removing wheat from the diet
If a wheat allergy and celiac disease have been ruled out, but irritable bowel symptoms are still present after eating wheat, you may consider removing wheat from your diet. Try tracking your diet with a food and symptom diary. Consider doing a _provoked symptom test _(re-exposure) by eating wheat and then observing if any symptoms are produced. This is a way to find out whether wheat is really responsible for the symptoms.
Some people who experience an improvement of their symptoms after eliminating wheat from their diet may not be sensitive to wheat itself, but rather to FODMAPs. FODMAPS are not only found in various types of grain, but also in legumes, fruits and vegetables. For this reason, it may be worthwhile for people with IBS to try out a low-FODMAP diet.
How to recognize food intolerances
It’s not always easy to identify food intolerances. Many people with IBS tend to severely restrict their diets because they are afraid of triggering IBS symptoms. This poses the risk of an unbalanced diet. For example, some people report that they only eat one or two different foods for weeks because they are afraid of symptoms.
Many food intolerances become apparent shortly after having eaten the food, making them easy to recognize. While intolerances are more subtle and show up hours or even days later. Certain foods, such as FODMAPs, stay in the colon for two to three days before causing discomfort. In order to identify such intolerances, it helps to track symptoms in a food and symptom diary for a limited time. This is the only way to recognize personal intolerances, since diagnostic tests don’t exist for every food intolerance or sensitivity.
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